A non-biodegradable, unitary drainage device of flexible character. The invention features a monolithic, skeletal construct consisting of stacked, planar or poly-formational arrays of quasi-tubular, tube or rod supports, termed "stand-off" elements. Actual positioning of the supports in their arrays is varied, with parallel interleaving, cross-linking and intertwining of supports to acquire varying degrees of strength and flexibility. Depending on specific function to be performed, optional covering sheet(s) of differing materials, that provide either particulate filtering or fluid impermeability (sealing), may be used with the various matrices. A different modality is also shown, wherein rods are mixed with tubules or perforated tubes to acquire the analogous structures, for use with great overburdens of stone or soil.